This invention relates to medical devices for injecting living bodies and, more particularly, to safety features incorporated therewith. In particular, it relates to a carpule-using syringe assembly having a needle protected to minimize the chance of accidental needle-stick.
In U.S. Pat. No. 4,998,922 by Thomas C. Kuracina entitled SAFETY SYRINGE CAP MINIMIZING NEEDLE-STICK PROBABILITY which issued Mar. 12, 1991, a safety device for hypodermic needles and the like is shown. The inventions shown hereinafter are improvements thereto by inventors including and/or working with Mr. Kuracina. In the interest of simplicity herein, the teachings of that patent are incorporated herein by reference and the discussion of the background art will be kept to a minimum.
A typical prior art hypodermic syringe includes a barrel having a moving plunger therein. A needle having a sharp beveled tip extends from the end opposite the end of the barrel into which the plunger is inserted. The needle is covered by a removeable cap for safety purposes. The problem to be solved and avoided is the accidental sticking of users of the syringe by the tip after use where the tip may carry body fluids containing agents of hepatitis B, AIDS, and the like. Accidental needle stick is a very common problem in the health care industry and besides the risk of serious illness or even death as a result thereof, the insurance industry spends over a billion dollars a year in the testing of individuals who have been subjected to post-use needle stick.
The 1979 patent of Alvarez proposed a retractable plastic protective sleeve over the needle. The Alvarez sleeve has an inner hub which fits around the base of the needle and an outer hub through which the tip of the needle passes. The inner and outer hubs are connected by curved slats. When the needle is to be inserted into the body of a patient, the force required to move the sleeve from its extended position to its retracted position can be depicted as a straight line beginning with very little required force to initiate movement. Thus, there is really no actual safety from a large variety of ways in which accidental needle stick takes place. Even if the sleeve fully extends after use, a slight blow against a user or observer in the area will cause the sleeve to retract and the tip to stick the unfortunate person.
With respect to the action of the basic protective sleeve of the above-referenced Kuracina patent by comparison, a high degree of force is required to move the protective sleeve from its extended position covering the tip. Moreover, a spring-biased locking collar is added over the protective sleeve which all but prevents the protective sleeve from moving from its extended position covering the tip. The collar must be moved from its locked position to a retracted, unlocked position before the unique deformation qualities of the sleeve take effect. After use, the locking collar springs back to its locked position. Thus, in virtually all "accidental" contact with the tip end of a hypodermic syringe, actual penetration by the tip should be prevented.
Carpule-based systems are known in the art. As shown in FIG. 1, the basic elements are a carpule 10 and a two-ended needle assembly 12. The carpule 10 comprises a cylinder 14 of plastic or glass having an open end 16 and a capped end 18. The capped end is closed by a piece of plastic or rubber (not shown) held in place by a collar 20. The two-ended needle assembly 12 comprises a cap 21 sized to fit over the collar 20. A needle 22 having an injection tip 24 on one end and a carpule-piercing tip 26 on the other end is concentrically held by the cap 21. As seen in FIG. 1, the carpule-piercing tip 26 extends to just within the cap 21 while the injection tip 24 is extended for use in its normal fashion. Typically, there is a plastic cover 28 which snugly fits over the injection tip 24 and the needle 22 up to the cap 21. The cover 28 protects the needle 22 and injection tip 24 as well as providing a safe way in which to handle the two-ended needle assembly 12.
In use, the two-ended needle assembly 12 is placed over the capped end 18 of the carpule 10 and the two in combination are disposed in the syringe assembly 30 of FIG. 2 with the cover 28 and needle 22 extending through a hole 32 provided therefor. The syringe assembly 30 has a pressure member 34 threaded through the rear thereof in concentric alignment with the open end 16 of the carpule 10. By turning the knob 36 to tighten the pressure member 34 against the open end 16 of the carpule 10, the carpule 10 is forced against the two-ended needle assembly 12 causing the carpule-piercing tip 26 to pierce the rubber or plastic to the interior of the carpule 10. A plunger rod 38 extends through a concentric bore 39 in the pressure member 34. The inner end of the plunger rod 38 has a threaded concentric bore 40 which mates with a threaded rod 42 extending concentrically backward toward the open end 16 from a plunger member 44 disposed within the carpule 10. By pushing the plunger rod 38 forward to contact the threaded rod 42 and turning it in a tightening direction, the plunger member 44 is temporarily attached to the end of the threaded rod 42. As thus configured, the syringe assembly 30 in combination with the carpule 10 and two-ended needle assembly 12 acts like a normal syringe and can be used to inject fluid contained in the carpule 10 or to withdraw fluids through the needle 22 into the carpule 10. Moreover, they can be used several times and can be disassembled and reassembled for further use.
With a conventional Kuracina type protective sleeve, it is delivered as part of an assembly containing the needle 22. Unfortunately, as depicted in FIGS. 3 and 4, the hole 32 in the end of the syringe assembly 30 is too small to accept the two-ended needle assembly 12 if a Kuracina type protective sleeve is attached thereto. Even in those syringe assemblies 30 where the hole 32 is in the form of a slot, the size is too small. Obviously, new syringe assemblies 30 could be manufactured for use with two-ended needle assemblies 12 having a Kuracina type protective sleeve attached thereto. The problem is one of being able to employ the large established base of syringe assemblies 30 in which the hole or slot 32 is too small.
In a co-pending application entitled MEDICAL INJECTION DEVICES WITH SAFETY FEATURES filed on even date herewith, certain improvements to the Kuracina protective sleeve are disclosed. The inventions described hereinafter are modifications to the above-described two-ended needle assemblies 12 and the manner of attaching a Kuracina protective sleeve in its various embodiments so as to allow the large established base of syringe assemblies 30 in which the hole or slot 32 is too small to be employed with protected needles.
The 1964 patent to Armao (3,134,380) shows a spring-loaded collapsible protective sleeve carried by a two-ended needle assembly used to attach a needle to a carpule and is, therefore, relevant to this invention.
Other objects and benefits of the inventions disclosed herein will become apparent from the detailed description which follows hereinafter when taken in conjunction with the drawing figures which accompany it.